Core making machine



, April 21, 1959 Filed Sept. 15. 1954 ,c. L. SELBY CORE MAKING MACHINE 3Sheets-Sheet 1 I Ap 1959' c. SELBY 'coRE MAKING MACHINE 3 Sheets-Sheet 2Fi1ed Sept. 13. 1954 April 21, 1959 sELBY Z 2,882,565

Filed se t. 1:5. 1954 CORE MAKING MACHINE s sheets-shat s f liliil ihlUnited htates CGRE MAKING MACHINE Claude Leslie Selby, Birmingham,England, assignor to constructional Engineering Company Limited,Birmingham, England, a British company Application eptember 13, 1954,Serial No. 455,571

Claims priority, application Great Britain September 18, 1953 2 Claims.(Cl. 22-10) This invention relates to core making or core blowingmachines of the kind in which the divided material of which the coresare to be made, usually sand mixed with a binder, is fed into acontainer or magazine into which compressed air is admitted to blow orforce the sand through apertures in the base plate of the container andinto corresponding apertures in the core box leading to the cavity orcavities in which the core or cores is or are to be formed. It is suchmachines which are referred to in this specification as of the kind setforth.

Core blowing machines are known in which a cartridge is used to becharged with sand and fitted into the machine. Compressed air applied toone end of the cartridge blows the sand out of the other end into thecore box. This method is only suitable for lightly bonded core materialand the cartridge has to be removed from the machine forre-charging.Medium or heavily bonded core sands tend to become impacted at the coreblowing apertures owing to the ramming effect of the air pressure behindit.

In our'Patent No. 2,409,330 a core blowing machine is described in whichair is admitted to the container or magazine through small perforationsfrom an air belt surrounding the lower part of the container ormagazine. The many fine streams orjets into which the air is splitresult in a thorough mixing of air and sand as the sand is agitated by amechanical agitator.

According to one aspectof the present invention air isadmittedthroughperforations from an air belt surrounding the lower part of thecontainer or magazine and through an additional entry in the upper partof the container so arranged that the sand or other core material isagitated by the entering air and becomes intimatelymixed with it.

The term sand is-usedin this specification forconvenience and isintended to refer not only to sand but to other core materials.

The air entry near the upper part of the container is preferablytangential in a cylindrical or conical container so that a swirlingmotion of the air, and sand entrained with it, takes place inside thecontainer or magazine. In a preferred embodiment according to thepresent invention the agitation of the sand by this means is soeffective that mechanical agitation or stirring is unnecessary.

The air preferably also enters the lower wind belt tangentially for moreeven distribution of pressure around the periphery of the container ormagazine.

In many known core-blowing machines it is necessary to raise the airpressure in the container to a considerable value for satisfactorycore-blowing. This results in a considerable consumption of compressedair since the air charged into the container has to be released at eachcore-blowing operation. With improvement in this respect particularly inview the present invention from another aspect provides a core making orblowing machine of the kind set forth wherein the container is notnormally under pressure but is adapted for the momen- 2,882,565Patented. Apr zl 1959 tary admission of compressed air through entrymeans so directed that the entering air disturbs the sand within thecontainer from its normally quiescent state, agitates it and mixes itintimately with air, the rise in pressure within the container resultingfrom said pulse of air forcing sand throughthe base plate into the corebox.

An embodiment of the invention will nowbe described byway of example,withreference to the accompanying drawings in which Figure l is a front.elevation of a core-making or blowing machine accordingto-the-invention.

Figure 2 is a side elevation.

Figure 3 is a sectional side elevation on line 3-3 of Figure 1.

' Figures 4 and 5 are sectional plan views on lines i-.-4 and 5-5respectively of Figure 3.

Figure 6 is a fragmentary sectional view on line 6- -6 of Figure 5.

In the illustrated embodiment of the invention the sand container ormagazine is a cylinder 7 with its axis vertical and slidably supportedfor limited vertical movement by bearings 8 on upright guide pillars9.The pillars 9 are mounted at their lowerend on a base :10 and supportabove the cylinder a hopper 11 on to which sand for charging'thecylinder can be loaded. A horizontally slidable trap or door 12 normallycloses an opening 13 in the bottom of the hopper 11 through which sandcan be passed into the open upper end 14 r of the cylinder 7.

A platform 15 for a core box is slidably mounted on the pillars 9 belowthe-cylinder. Its height is adjustable by a screw jack 16 of substantialproportions. The nut 17 of the screw jack-is-provided with a hand wheel18 For vertically divisible core boxes lateral clamping means 21 may berequiredinaddition.

On raising-the platform 15 by angular movement of the jack handle 19 theuppersurface of the core box is brought into contact with the aperturedbase plate 2t) of the cylinder 7 whichisslightly lifted and urges arubber ring or grommet 22 811116, top of the cylinder into contactwiththe;s lida ble trap ordoor 12 thereby sealing the d pp rn of the l nd ;Q.1. Q P ;i cad e b y m smsnt i t eiads-hand 1191 nth o p i di e tion thecylinder falls with the core box to release the slidable trap door 12until it is arrested by stops 23 on the pillars 9. As the platform 15 islowered further the core box is released from the bottom of the cylinder7 and can be removed and opened for removal of the completed core.

As shown in Figures 3, 5 and 6 at the lower end the cylinder is providedwith a double wall providing a hollow annular compartment 25 to whichair can be admitted through an inlet port 29 arranged substantiallytangentiaily to the inner surface of the wall of the cylinder 7. Theinner skin 26 of the double wall is provided with a row of internallycountersunk holes 27 covered externally by gauze or finely perforatedmaterial 28 through which air can pass in fine jets or streams to beintimately mixed with the sand.

In a cylinder having a capacity of twelve pounds of sand a single row offive-sixteenths of an inch in diameter holes are used covered by sheetmaterial .024 of an inch thick perforated with one-thirty-second of aninch diameter holes spaced to provide about three hundred holes persquare inch.

As shown in Figures 3 and 4 through the side wall at the upper end ofthe cylinder 7 an additional port 30 arranged substantially tangentiallyto the inner surface of the wall (see Figure 4) is provided for airadmission. Pipes 31 leading to the upper and lower air inlets are joinedto a common compressed air feed line 32 controlled by a single valve 33preferably as illustrated of the spring-loaded plunger type or the likebiased to the off position.

One or more core blowing apertures 34 is provided in the lower end faceof the cylinder to correspond in number and size with the openings inthe core boxes to be blown. I

In operation sand is loaded on to the hopper 11 while the machine is inthe unclamped position. The slidable trap or door 12 is opened to allowsand to be moved into the interior of the cylinder. A core box is placedon the platform 15 which is appropriately adjusted for height and thenclamped sealing the top and bottom openings of the container. Compressedair is admitted to the cylinder momentarily by the valve 33 to fill'thecore box. The machine is unclamped, the core box removed, opened and thecore taken out, the core box replaced and the operation repeated asoften as necessary. When the machine is unclamped any air remainingunder pressure in the cylinder 7 is discharged by the release of therubber ring seal 22 at the top opening 14 of the cylinder.

The combination of air entry in fine jets or streams from the lower airbelt and the swirl efiect produced by the tangential top air entryprovides the necessary agitation of the sand to ensure intimate mixingwith the air and makes mechanical agitation unnecessary.

This embodiment according to the present invention is simple toconstruct and not costly. It enables cores to be blown of a size withinthe total capacity of the container in a very short time, which in thecase of a machine having a container capacity of twelve pounds andoperating on a compressed air line pressure of ninety pounds per squareinch is of the order of one second. It is especially suitable for smallcores of which a large number may be very rapidly blown at each fillingof the cylinder. Cores can be made of any material normally used forcore blowing, including medium bonded core sand, synthetic mixtures andshell mould mixtures.

A conical hopper may be employed in place of the construction shown inFigures 1 to 3.

Other forms of horizontal clamps for the core box may be employed thanthat shown generally at 21. For example, a cam-ended lever pivotedeccentrically at the back of the fixed part of the clamp 21 with the campassing through a slot so that its periphery bears upon the clampingface 21a, the single lever swinging in a plane perpendicular to theplane containing the clamping face 21a. The clamps may be operated bycompressed air.

4 Compressed air may also be employed for raising the core box platform15.

If desired a bat-lie disc, raised above the blowing aperture 34 byprojections on its under side as shown at 35 may be employed, to preventdry material running out of the machine but permits material underpressure to pass around its peripheral edge to the aperture 34.

I claim:

1. In a core-making machine the combination of a cylindrical sandcontainer, means for supporting a core box below the container, anaperture sand delivery plate at the base of the container, means forsupplying air under pressure to the container for forcing sand throughsaid aperture plate into the core box, entry means for admitting suchair under pressure at the lowest part of the cylindrical wall of thecontainer for permeating with air a body of sand within the containerand additional entry means for simultaneously admitting air to the upperpart of the container the interior of which it enters in a directionsubstantially along the adjacent interior surface of the container, abase, spaced upright columns mounted'on said base, a sand hoppersupported by said columns above the container having an opening for thepassage of sand in register with an aperture in the top of thecontainer, a movable trap slidably mounted on said hopper and closingsaid opening, sealing means on said container for the joint around saidaperture and between said trap and the top of the container, guide meansslidably supporting said container on said columns for limited axialmovement relative to the hopper, means for clamping said containerbetween said hopper and said core box supporting means to cause saidsealing means to engage said trap and seal the joint thus enabling theinternal pressure of the container to be raised and for unclamping saidcontainer to open the joint, to release any residual pressure within thecontainer and to enable the trap to be opened.

2. A core-making machine according to claim 1 wherein the means forclamping the container axially is constituted by the means forsupporting the core box below the container, and said supporting meanshas a movable portion slidably mounted on said columns.

References Cited in the tile of this patent UNITED STATES PATENTS FeaIan. 23, 1951

